Answer this question truthfully
### Question: Who is at highest risk for Costello syndrome ?
### Response: Because Costello syndrome typically occurs as the result of a new mutation, family members are, for the most part, not at increased risk. In some cases, however, depending on the genetic make-up of the parents, siblings of people with Costello syndrome may be at risk for the condition.
In addition, although people with Costello syndrome typically do not reproduce, if they were to reproduce, the chance of passing the condition to their offspring is 50%.